[llvm] [NFC][SPIRV] Fix SPIRV backend build (PR #101081)

[Justin Bogner via llvm-commits]

https://github.com/bogner commented:

I think we might be able to do this by getting rid of SPIRVMachineModuleInfo entirely - the only thing we actually need for the SyncScope stuff is an LLVMContext.

https://github.com/llvm/llvm-project/pull/101081